Belt tensioners are used to impart a load on a belt. Typically the belt is used in an engine application for driving various accessories associated with the engine. For example, an air conditioning compressor and alternator are two of the accessories that may be driven by a belt drive system.
A belt tensioner comprises a pulley journaled to an arm. A spring is connected between the arm and a base. The spring may also engage a damping mechanism. The damping mechanism comprises frictional surfaces in contact with each other. The damping mechanism damps an oscillatory movement of the arm caused by operation of the belt drive. This in turn enhances a belt life expectancy.
Representative of the art is U.S. Pat. No. 5,632,697 to Serkh (1997) which discloses a spring activated damping mechanism which provide a normal force greater than a spring force applied to a brake shoe that engages a cylindrical member.
Reference is also made to co-pending U.S. patent application Ser. No. 09/861,338 filed May 18, 2001 which discloses a tensioner having a damping mechanism.
Reference is also made to co-pending U.S. patent application Ser. No. 09/864,536 filed 24, May 2001 which discloses an asymmetric damping tensioner belt drive system.
What is needed is a damping mechanism having an asymmetric damping factor in the range of approximately 1.5 to 5.0. What is needed is a tensioner having a damping mechanism comprising two members having a pivotal connection. The present invention meets these needs.